Im a bit unclear on what exactly assigning a coordinate system does in the model space of autocad we are using 2015 civil 3d. I found some mention of scale factor as a function of latitude in the mercator projection, and in mercator projection the scale factor is changed along the meridians as a function of latitude to keep the scale factor equal in all direction. When project data does not lie at a point where the scale fac. There is also local scale factor to worry about, if you want to be accurate. The world is divided into 60 north and south zones, each six degrees wide. If you know what zone you are in, then the coordinates pinpoint you in the world. The universal transverse mercator utm coordinate system was developed by the department of defense and is a global coordinate system with 60 northsouth zones. Each zone width is 6 degrees, which creates a scale difference of no more than 1. Because utm projection and gausskruger projection have the same character, so there is a similar exchange relation between them. The utm zones nearly cover the earth except for the polar regions which are covered by the universal polar stereographic, or ups, projection.
The center line of a utm grid zone has a scale factor of 0. Projections and scale factors geonet, the esri community. In the ellipsoidal model, a stereographic projection tangent to the pole has a scale factor of less than 1. In utm coordinates, it can be as large as 1 part in 2500. So when you are entering these, pay extra attention. One of the most widely used map projection and grid systems is the universal transverse mercator utm system. Each zone width is 6 degrees, which creates a scale. If the boundaries of the utm zones were parallels to the central meridian, what would the scaling factor be for distances along the borders from the sphere to the projection. At the end of the work day, all sectorsindustries have their own different needs, necessitating different map projections. How typically a scale factor is used on a construction site. The ellipsoid and the transverse mercator projection geodetic information paper no 1 21998 version 2.
Utm zones are flattened using the transverse mercator projection, and a rectangular grid network of straight horizontal and vertical lines is superimposed on each zone. Utm coordinates are mapping coordinates, but you can easily use them as plane coordinates. Feb 09, 20 arcgis desktop doesnt have a tool to calculate the point scale factor for a map projection like transverse mercator. The universal transverse mercator utm system is a specialized application of the transverse mercator projection. Utm is also a conformal projection meaning that it preserves angles locallypreserves shapes of small areas.
Both and can be evaluated for the coordinates in the transverse mercator and lambert conformal projections using the respective formulas defined in linzs25002. Utm is founded on a secant transverse mercator projection. In this paper we will study the effect of distortion caused by scale factor and trying to get the scale factor relationship between etm and utm systems in egypt. Tab to the forward calculation to perform the calculations. The universal transverse mercator utm coordinate system, which uses the transverse mercator projection, has a scale factor of 0. Please recall that spcs zones are usually more limited in width, 158 miles, and, therefore, have a smaller range of scale factors than do the utm zones. The ellipsoid and the transverse mercator projection.
The universal transverse mercator utm is a system for assigning coordinates to locations on the surface of the earth. Utm zones extend from 80 degrees south to 84 degrees north. The combined factor used to scale ground distances to the mapping plane. Although meridians inside the zone and on zone boundaries converge towards. If a measurement was taken between two points along the central meridian while using the universal transverse mercator utm. Isotropy of scale implies that small elements are stretched equally in all directions, that is the shape of a small element is. The universal transverse mercator is horrible for smallscale lessdetailed maps like world atlases and perfect for mapping narrow regions. The parallels of latitude are scaled by a factor of 0. In the utm projection, the central meridian has scale factor of one from the sphere to the projection. In this months column, well take a look at the utm system, see how utm grid coordinates are related to. Universal transverse mercator utm coordinate system cylindrical conformal true scale along central meridian, which points at geographic north, or along two lines equidistant from the central meridian which do not point at geographic north.
The parameters needed to convert to or from utm zone 15 are shown below. The universal transverse mercator is slightly smaller than the calculations using all four methods for finding a distance in a utm projection. The universal transverse mercator utm coordinate system is a specialized application of the transverse mercator projection. However, for conformal projections, the scale factor of the projection is independent of the direction of the line and depends only upon the location of the point. Mar 03, 2015 and at last for computing grid scale factor or combined scale factor, you should multiply kefgrid factor. Arcgis desktop doesnt have a tool to calculate the point scale factor for a map projection like transverse mercator. Oct 01, 2016 how to calculate scale factor in land surveying a map projection provides a means of representing the curved surface of the earth on a plane surface so that coordinate grids can be defined and maps drawn.
It is impossible to map a curved earth on a flat map using plane coordinates. Coordinate conversions and transformations including formulas. Universal transverse mercator utm projection geohub. Being geospatiallyfriendly involves the ability to accurately, precisely. For example, for the wgs 84 utm zone 31n coordinate. Grid factor is used to convert length from surface of earth into projection system utm and if you want convert utm length into earth surface length you should divide length into the grid factor. This manual describes geographic to grid and grid to geographic conversions. Universal polar stereographic coordinate system wikipedia. Utm projection divides the earth into 60 zones each 6. The projection from spheroid to a utm zone is some parameterization of the transverse mercator projection.
Handbook for transformation of datums, projections, grids and. To transfer data from one to the other system, the projection scale factors are different for the two systems and ignoring it in these transformations can led to large errors. The point scale factor gives a linear distortion at the specific location on the specified map projection. In state plane coordinates, the scale factor is usually no more than 1 part in 10,000. Universal transverse mercator coordinate system wikipedia. Wisconsin falls within utm zone 15 and 16 about equally.
Scale factor is a unitless value applied to the center point or line of a map projection. In utm, the central meridian now has a relative scale of 0. Sep 29, 2017 utm is also a conformal projection meaning that it preserves angles locallypreserves shapes of small areas. Projection scale factor, map distortion, etm system, utm system, geodetic datum, geodetic. Handbook for transformation of datums, projections, grids. The standard international coordinate projection system used with many different map datums. This projection is sometimes referred to as a modified mercator. As the name suggests, the universal transverse mercator projection is based on the cylindrical transverse mercator projection. A utm corner ruler consists of two scales at right angles to each other. Then click the set up parameters button to set up the parameters for the appropriate utm transformation. Universal transverse mercator utm coordinate system. Use of the 3tm or utm projection for the cad file is dependent on whether the survey falls.
Finally, a worked example of a traverse connecting two known. More detailed examples showing complete conversions are shown in the nad83 minnesota county coordinate system section of this. In a transverse mercator projection, the central meridian would normally have a relative scale of 1. Polar regions use the universal polar grid system to be discussed in a different post. Input the geodetic datum, and the latitude and longitude that you want to transform. The universal transverse mercator utm coordinate system is a specialized. Other projections such as utm and state plane are designed for focused areas of the globe in order to keep the distortion minimal. I made my own version of the projection i needed, entered the scale factor value in the scale factor parameter for the projection and also multiplied the scale factor by the false easting and used that value instead of the default false easting for the ky projection. This gives cartographers a map to work with always in meters.
This can also be found in deakin 2005a and the gda technical manual. Sep 08, 2014 utm coordinates usually have lots of digits. The utm coordinate system is a universally used plane coordinate system except for polar regions. Scale factor at central meridian this is the ratio of map scale along the central meridian and the scale at a standard meridian, where scale distortion is zero. Instead, it was engineered for convenience in working with cached map tiles. The scale factor at the central meridian is specified to be 0. Universal transverse mercator utm zones false northing, false easting. The utm projection flattens the sphere 60 times by shifting the cylinder central meridian 6 for each zone. This will be followed by a discussion of scale factors point scale factor and combined scale factor and the reduction of distances to the utm projection plane. Finally, a worked example of a traverse connecting two known points pms with grid coordinates will be shown. Since all projections treated in this technical report are conformal, the scale of the projection will be referred to as the point scale factor k. Pdf optimal scale factor on the central meridian for a 2tm map. The universal transverse mercator utm projection the transverse mercator tm projection is a conformal projection, i.
Because of the increasing use of satellite navigation systems a short description of the shape of the earth and its mathematical representation are given as well as the constants for the projection. Measuring distances and areas when your map uses the. The parameters vary by nation or region or mapping system. In such a projection, instead of projecting the complete globe into a flat surface, each of the 60 strips or zones gets projected onto a plane separately, therefore minimizing scale distortion within each zone.
The cylinder in the transverse mercator projection is tangent along a meridian line of longitude or it is secant, in which case it cuts through the earth at two standard meridians. The globe is divided into 60 north and south zones, each spanning 6 of longitude. Relationship and applications of utm projection and gauss. In the utm projection the transverse cylinder rotates by 6 increments, thus creating 60 360 6 strips or projection zones. There is a reference for utm grid coordinates within each zone.
I would like to know how to calculate the scale factor in my region utm zone 28 with central meridian of 15 degrees, given a control point of latitude 8. This can become part of a file used in arcinfos project command. Each zone has its own central meridian and a scale factor of 0. Is there no distinction between ns and ew distances, then. Jan 28, 2014 bangladesh map projection systems with parameters bangladeshs longitude is from about 88. Scales and transformations nature of geographic information. The parameters are identical to mga, therefore users often select utm where mga may not be an available option in their software or gnss receiver setup menu.
As a preliminary, a brief description of the utm projection and some terminology and equations will be given. An abbreviated or truncated utm grid reference gr is. Distances are accurate along the central meridian if the scale factor is 1. Project latitude and longitude to grid eastings and northings for any transverse mercator map projection, including the ordnance survey national grid and vice versa. Therefore, utm is a conformal transverse projection. Universal transverse mercator utm coordinate system cylindrical conformal true scale along central meridian, which points at geographic north, or along. Like the traditional method of latitude and longitude, it is a horizontal position representation, which means it ignores altitude and treats the earth as a perfect ellipsoid. As with the mercator projection, the region near the tangent or secant point on a stereographic map remains very close to true scale for an angular distance of a few degrees. This means that a distance of 100 meters on an ellipsoid would be 99. Usually the projection parameters are concluded origin central meridian and standard parallel, false easting, false northing and the scale factor at central meridian.
An abbreviated or truncated utm grid reference gr is stated becomes dependent on x. Influence of the scale factor on the projection stack exchange. True meridional arc developed meridional arc a x f straightline direction joining two points on the projection. Utm projection divides the earth into 60 zones each 6 degrees of longitude wide. Ijce relationship of etm and utm projection scale factors.
The scale factor will be practically the same for wgs84. The small circles have a scale factor of 1, meaning a distance of 100 meters in the ellipsoid would be the same on the map projection. A scale factor accounts for a true horizontal ground distance on a surface of the earth and the same distance when projected onto a mapping plane or grid. The point scale factor is the scale factor at a point that changes with increasing distance from the central meridian.
Transverse mercatorproperties of maps documentation. The design of a map projection often results in one or more places where the scale factor is held constant equal to 1. Once the value of k is defined,the value of m can be got,so they can be transformed according to the scale factor. The relation between the projection coordinate formulas of them is. Utm corner rulers will typically provide an additional digit of precision beyond a utm grid overlay.
Compute local scale factor and grid convergence at any point on the grid, and compute tt and true. In egypt universal transverse mercator utm and egyptian transverse mercator etm are used for production of maps. Our local county coordinate systems have a scale factor associated to with the projection something along the lines of 1. Many gps receivers can directly output position information in utm coordinates. Drawing objects with utm coordinates student project. In the utm projection, the central meridian has scale factor of one from the sphere to the.
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